Means for introducing objects in an isolated enclosure



Feb. 6, 1968 J. ROMAND ET AL 3,368,191

MEANS FOR INTRODUCING OBJECTS IN AN ISOLATED ENCLOSURE Filed June 22,1964 3 Sheets-Sheet 1 J. L. ROMAND ET AL 3,368,101

MEANS FOR INTRODUCING OBJECTS IN AN ISOLATED ENCLOSURE v Feb. 6, 1968Filed June 22, 1964 SSheets-Sheet 2 Feb. 6, 1968 J. L. ROMAND ET AL3,368,101

MEANS FOR INTRODUCING OBJECTS IN AN I SOLATED ENCLOSURE Filed June 22,1964 3 Sheets-Sheet 5 1' Q Q a; u.

3,368,101 MEANS FOR INTRODUCING OBJECTS IN AN ISOLATED ENCLOSURE JacquesLouis Remand, BourgJa-Reine, and Boris Vodar and Jean Martin, Paris,France, assignors to Centre National de la Recherche Scientifique(French Government Administration), Paris, France Filed June 22, 1964,Ser. No. 376,882 Claims priority, application France, June 25, 1963,939,304 11 Claims. (Cl. 314-1) This invention relates to transportingdevices and more specifically to devices for inserting an object in agasfilled or evacuated container without disturbing the characteristicsof the medium therein.

Many industrial and research operations require the introduction of anobject or a test sample into an enclosure containing a gaseous mediumwhose composition and/or pressure differ from those of the mediumoutside the container. For such operations it is often desirable, if notessential, that the medium within the enclosure not be disturbed.

This condition is particularly important in spectographic analysis sincetest sample electrodes must be introduced into the chamber of thespectroscope while, for each test run, the vacuum pressure is maintainedat a predetermined value in order to permit the production of uniformarcs and, hence, the achievement of accurate and repeatable results.

It is therefore an object of this invention to introduce an object intoa container without disturbing the medium therein.

It is another object of this invention to accomplish such introductionusing relatively simple means.

It is a further object of this invention to accomplish such introductionby a simple and rapid procedure.

Although the physical embodiments of the present invention disclosedherein are shown in connection with a spectroscope, it should beunderstood that this is only by way of example and that the presentinvention may equally well be used with any other device requiring theperformance of a similar operation under similar circumstances.

The preferred embodiments of the present invention essentially comprise:

A piston which is slidably and rotatably movable within a cylinder whichisrigidly attached to the wall of the enclosure, said pistoncommunicating with the interior there of by means of a circular,off-center opening arranged in the base of the cylinder and closing thecylinder at the end within the enclosure, said piston being pierced by alongitudinal passage which is displaced from the cylinder axis by adistance equal to the radial displacement of said offcenter opening fromthis axis, the longitudinal passage being designed to receive objectswhich are to be introduced into the enclosure, the interior end of thispassage being capable of being placed, by means of both translationaland rotational movements of said piston, either adjacent to said openingor against an air tight seating formed in said cylinder base;

A closure system acting on the outer extremity of said passage andcapable of assuming, with respect to the piston, either a first positionin which said outer extremity of said passage is open to permit objectsto be placed in said passage, the interior end of the passage then beingin contact with said seating, or a second position in which the closuresystem seals the outer extremity of said passage, the closure systemcomprising means for pushing objects in said passage into said enclosureafter the piston has been rotated into a position where it is adjacentto said opening in said cylinder base; and

States Patent 3,358,1M Patented Feb. 6, 1968 ice thereof. These membersare preferably maintained away from the longitudinal path in order toprevent them from contaminating the test samples.

The above described device is also intended to be used with auxiliaryunits which will preferably be operated at the same time and which willbe described in detail at a later point herein.

The present invention is particularly directed to a certain use of theabove described structure, as well as particular forms of constructionthereof, and more particularly to the structures embodying the presentinvention and the combination of these structures with suitable systemsfor carrying out various multi-step processes in an enclosed space.

These and other advantages, objects and features of the presentinvention, will become more readily apparent from the following etaileddescription when taken together with the accompanying drawings, inwhich:

FIG. 1 is a partially cross-sectional view of a spectroscoperepresenting one preferred embodiment of the present invention, theplane of the view being taken perpen dicular to the axis along which theradiation from the sample is observed;

FIGS. 2 and 3 show longitudinal cross-sectional views of one embodimentof a subcombination of the present invention shown in two differentoperating states;

FIGS. 4 and 5 show cross-sectional views, taken along respectivemutually perpendicular planes, and in two different operating states, ofanother subcombination of the present invention.

On the drawings the same numeral is used to identify the same elementappearing in several figures.

According to the present invention, it is proposed to construct a devicefor introducing into the spectroscope chamber 1 of FIG. 1 an electrode 2constituted by a test sample which is to be submitted to a spectroscopicanalysis.

The spectroscope chamber 1 is here shown, by way of example, as being inthe form of a horizontal cylinder. The view of FIG. 1 is takenperpendicular to the cylinder axis, which axis coincides with the linealong which one observes the spectrum produced by the test sample. Thevertical direction in the plane of FIG. 1 is shown by line X-X.

In front of the plane of FIG. 1 the chamber 1 is furnished with a flatbase plate which is readily removable to permit the cleaning and generalmaintenance of the elements therewithin. To the rear of this plane thechamber is provided with a second base in which is formed the entry slit1a for the spectrograph. In order to produce the necessary degree ofvacuum within the chamber 1, it is provided with a pump orifice 1b whichwill be connected to a suitable vacuum pump (not shown), any known typeof vacuum pump being suitable for this purpose.

In order to generate an arc, chamber 1 com-prises an arrangement wellknown to the prior art which consists of a current input 3 electricallyconnected to electrode 2 through the intermediary of 'anelectrode-carrying slip 2a composed of two semicylindrical halves 20which are pressed toward one another, and hence against electrode 2, bya fiat spring 2b, as well as an arc initiating element 4 supported by apost 6 which is electrically grounded, the arc initiating element beingformed by a common cathode 5 electrically grounded and, by an interiorelectrode or starting anode 7, connected to an electrically isolated andair tight current output terminal 7a.

In order to prevent any variation in the composition or pressure of thegas Within chamber 1 at the time of 3 an insertion of a new electrode 2,the chamber is furnished with an electrode insertion unit whichrepresents a preferred embodiment of the present invention and whichextends through a circular opening 14 in chamber 1, the opening beingdefined by flange 15. This unit is shown in detail in FIGS. 2 and 3.

The spectroscope is also furnished with a unit passing through chamberopening 38 for correctly positioning electrode 2 for each spectrogramand for causing the test sample to be released from clip 2a when it isdesired to change electrodes, and with a unit in communication withchamber opening 51a for recovering electrodes after their release fromclip 2a. and for permitting the recovery of these electrodes withoutdisturbing the chamber atmosphere. One form of this latter unit is shownin FIGS. 4 and 5.

Turning now to the sample introduction unit which is the subject of thepresent invention, FIGS. 2 and 3 show a piston 8 which is both rotatableand longitudinally slidable in a cylinder 9 immovably attached tochamber 1 and communicating with the interior of this chamber through anoff-center circular opening 10 arranged in the base of the cylinder, thecylinder axis being indicated by the broken line Y-Y. The piston 8 ispierced by a longitudinal passage 11 whose axis is displaced from lineY-Y by the same distance as is the axis of opening 10. The passage 11 isdesigned to receive electrodes 2 which are to be introduced intochamber 1. The inner end 11a of this passage is capable of being placed,by means of rotations of piston 8, either in contact with an air tightseating 12 or adjacent the opening 10. When the piston is in this latterposition, it may be slid forward so as to move passage end 11:: furtherinto chamber 1.

The unit also comprises a closing assembly which cooperates with theouter extremity 11b of passage 11 and which is movable in such 'a mannerthat it can either be clear of extremity 11b so as to permit theintroduction of test samples into housing 11 (as shown in FIG. 3), atwhich time inner extremity 11a abuts against seating 12, or it may be ina closing position where it seals extremity 11b, thus isolating passage11 from the exterior (FIG. 2). Means are also provided which, when theassembly is in its closing position, can be manipulated to urge theelectrode 2 in housing 11 into the interior of chamber 1, after piston 8has been rotated so as to be pposite opening 10.

In the specific structure shown in FIGS. 2 and 3, the cylinder 9 isrigidly fastened in chamber opening 14, the opening being bordered by aflange 15 against which abuts a sholulder 16 provided on the outer wallof cylinder 9, the imperme'ability of the joint being assured by anannular seal '17. Then end of cylinder 9 directed towards the inside ofchamber 1 is partially closed by a plate 18 which carries an impermeableseating 12 and an opening 10, both of which are circular and are placeddiametrically across from each other symmetrically with respect to theaxis YY of the cylinder.

The piston 8 is free to slide longitudinally and to rotate in cylinder 9while maintaining an impermeable contact with the cylinder with the aidof annular seals 20, and it carries, on its face directed towards theinterior of chamber 1, an off-center extension 21 forming a tube theextremity of which defines the end 11a of passage 11. The extension 21,whose outer diameter matches the diameter of opening 10, can eitherextend through opening into the interior of chamber 1 (FIG. 2) or canabut against seating 12 (FIG. 3), the latter position causing the end11a of passage 11 to be sealed so as to completely isolate chamber 1from the exterior, this sealing being effected by the abutment of theextremity of extension 21 against seating 12, the abutment beingrendered air tight by the flexible annular seal 19. Seal 19 has aninternal diameter which is greater than that of passage 11 so that,during the periods when the extension 21 abuts against the seal,electrodes placed in the passage will not be in danger of beingcontaminated by contact with this seal, such contact being often capableof causing contamination because the seal members are often suppliedwith a lubricant. At the opposite, or outer, end 11b of the passage, thepiston 8 is furnished with a boss 22 containing a pin 13 from which ispivotally mounted the passage closing assembly contained within ahousing 23 and comprising an extension 24- directed towards piston 8. Acanal 25 passes longitudinally through said housing so that one end ofthe canal opens onto the extremity of extension 24 and the other endcommunicates with an aligned passage in a vacuum pump connection 26attached to the end of housing 23 furthest removed from extension 24.

The extension 24 is so designed that when it is in its closing positionit forms, in cooperation with seal 27, an air tight joint with theextremity 11b of housing 11. Seal 27 is mounted away from the path to befollowed by electrode 2 or by mechanical pushing means in order toeliminate any possibility that the electrode might be contaminated bycontact with the seal. An impermeable contact is assured between housing23 and connection 26 by seals 21a. Mechanical electrode pushing meansare provided in the form of a shank 28 carried on a toothed rack 29which is capable of being moved along canal 25 under the action of apinion 30w driven by an external hand crank 30 by means of a shaft whichextends in an air tight manner through the wall of housing 23. Thelocking of housing 23 in its closed position is assured by a bolt 31which is manipulated by handle 32 and which bears against the front wallof the boss 22 of piston 8 (see FIG. 2). With bolt 31 in this position,any attempts to rotate housing 23 would be opposed.

The device just described functions in the following manner: Assumingfirst that the device is in the position shown in FIG. 2, the extension21 of piston 8 extends through opening 10 into the interior of chamber1, the canal 25 is in communication with, and aligned with passage 11,and the same vacuum exists in chamber 1, passage 11 and canal 25. It isthen possible to cause shank 28 to move electrode 2 into chamber 1 andbetween the halves of clip 2a into the position shown in FIG. 1.

When this operation is completed, the shank will be withdrawn back intocanal 25, the assembly of piston 8 and cylinder 9 will be slid backwarduntil the end 11a of extension 21 is fully within housing 23, whichcondition will be indicated by the abutment of a shoulder 33 on piston 8against an annular stop member 34 carried on cylinder 9. Stop member 34has one sector removed so as to permit the correct operation of thedevice. The pistonhousing assembly is then rotated by 180 around axisY-Y so that end 11a is placed opposite, but out of contact with, seating12. When the force applied to slide the assembly backward is thenreleased, the pressure diiference between the normal atmosphere and thevacuum inside chamber 1 will act on piston 8 so as to force end 11aagainst seating 12. At this time, the passage 11 is completely isolatedfrom the interior of chamber 1 and air is permitted to enter passage 11and canal 25 through connection 26. The bolt 31 is unlocked by arotation of handle 32 (counterclockwise in FIG. 2) and the housing 23 isrotated about pin 13 into the position shown in FIG. 3. In this positionthe unit is prepared to receive a new electrode 2 for introduction intochamber 1. In order to avoid any possible damage to the unit as a resultof the conceivable rotation of housing 23 around pin 13 before thewithdrawal of shank 28 into canal 25, a safety device has been providedto render impossible any movement of handle 32 before the completewithdrawal of shank 28.

When a new electrode 2 has been introduced, housing 23 is rotated backinto its closing position so that extension 24 bears against end 11b ofextension 21, bolt 31 is placed in its locking position, a vacuum pumpis connected to the end of connection 26 and is operated so as toproduce a vacuum in canal 25 and passage 11, piston 8 and housing 23 arepulled backward by a small amount so as to permit extension 21 to clearseating 12, the unit is rotated by 180 around axis YY so as to bring end11a of passage 11 into alignment with opening 10, and the assembly isallowed to slide forward, under the effect of the vacuum in chamber 1,causing extension 21 to enter the interior of chamber 1 until piston 8abuts against the inner wall 18 of cylinder 9. The unit is then onceagain in the condition shown in FIG. 2.

After the placement of each electrode in clip 2a, extension 21 isretracted into cylinder 9 and piston 8 is rotated until end 11a isopposite seating 12 before the commencement of an analysis run in orderto eliminate any risk of an are damaging extension 21, or the productionof a short circuit through extension 21.

In order to properly position an electrode in the chamber, and in orderto open and close clip 1 to permit it to receive new electrodes andrelease used ones, means are provided which are illustrated in FIG. 1.Within chamber 1 is provided a shaft 35 the interior extremity 36 ofwhich is in the form of a screw driver blade or similar flattened shape.The shaft 35 may slide within a guide 37 placed in an opening 38 inchamber 1, this opening being approximately diametrically opposed tochamber opening 14 and the shaft 35 being essentially parallel with, butaxially displaced from, passage 11. Opening 38 is closed by a plate 39and the impermeability of the joint between chamber 1 and this plate isassured by an appropriate seal 40. Another seal 41 assures theimpermeability of the joint between shaft 35 and guide 37. Externally ofchamber 1, shaft 35 is terminated by a curved extremity 42 which extendsradially from an external guide tube 43. Guide tube 43 is furnished witha pair of notches 44a and 44b in which the curved end 42 of shaft 35 maybe engaged in order to place the inner end 36 of shaft 35 into any oneof several predetermined positions. Near its end 36, the shaft 35carries a disc 45 disposed perpendicular to the direction ofdisplacement of the shaft and provided with a peripheral ramp, or cam,46, the purpose of which will become apparent from the followingdescription of the operation of the above described device.

Prior to the introduction of an electrode into chamber 1, shaft 35 isplaced in a position in which its curved end 42 is seated in notch 44aand in which its inner end 36, in the form of a screw driver blade, isinserted between elements of clip 2a.

Electrode 2 is at this time introduced into the chamber and is forcedbetween clip elements 20, under the urging of shank 2.8, so that itspreads these elements apart and advances between them until its leadingedge comes in contact with disc 45. The electrode is then correctlypositioned. Shaft 35 may then be withdrawn as far as possible and lockedin its retracted position with its end 42 engaging notch 44b. Theextension 21 of piston 8 may also be retracted and seated in seating 12.The spectroscope is now prepared to obtain spectrograms of the electrodematerial.

After one or several test runs, when it is desired to work with a newelectrode, the shaft 35 is first returned to its advanced position whereend 42 engages notch 44a and screw driver blade 36 is inserted betweenelements 2c of clip 2a. In order to free electrode 2 from the clip, itis only necessary to rotate shaft 35 through a small angle, 45 forexample, so that blade 36 spreads the two halves 2c apart, while at thesame time the camming periphery 46 of disc 45 bears against the frontend of electrode 2 so as to exert a sufficient transverse force to causeit to disengage from the clip 2a.

The spent electrode will then fall into the recovery device indicatedgenerally by reference numerals 47, 48, 49, 50 in FIG. 1 and shown indetail in FIGS. 4 and 5. Referring specifically to FIGS. 4 and 5, onepreferred embodiment of the recovery device is shown to have a recoveryfunnel 47 disposed directly below clip 2a and mounted on an air lock 48which is inclined with respect to the vertical, indicated by line X-X,and which is placed below funnel 47. Air lock 48 comprises a receptacle49, which may be made of a transparent material, or with transparentsections, and which is intended to serve as a temporary storagecontainer for used electrodes. Receptacle 49 is maintained in place withrespect to air lock 48 by means of a readily detachable stirrup element49a. The recovery unit is attached to chamber 1 by means of acylindrical extension 50 of connecting element 53 which is rigidlymounted in contact with the inner cylindrical wall of an opening 51. Theopening 51 ends in a flange 51a which is impermeably joined toconnecting element 53. The impermeability of the conr nection is assuredby interposal seal 52. In a like manner,

seals 54 assure the air-tightness of the joints between air lock 48 andthe elements connected at each of its ends.

Air lock 48 comprises a hollow internal region 55 which can communicatewith the interior of chamber 1 by way of passage 50a passinglongitudinally through the connecting element 53 and its extension 50.This communication may be interrupted by the rotation of plug 56 againstseal 60 so as to impermeably isolate region 55 from passage 50a, whichrotation is effected from outside air lock 48 by means of rotating lever57 whose passage through the wall of air lock 48 in an airtight manneris assured by seal 61. Internal region communicates with receptacle 49through a permanently opened opening 58, the impermeability of theconnection between elements 48 and 49 being assured by annular seal 59.Finally, a vacuum pump orifice 48a is provided in air lock 48 incommunication with region 55 so as to permit the latter region and theregion enclosed by receptacle 49 to be evacuated of air prior to theremoval of plug 56 from the mouth of passage 50a.

Prior to the start of a series of analyses in chamber 1, plug 56 sealspassage 50a until the internal regions of elements 48 and 49 have beenevacuated. Plug 56 is then rotated into the open position shown in FIG.4 and is maintained in that position during the entire period ofoperation of the spectroscope, or until receptacle 49 becomes filledwith spent electrodes.

Each time an electrode is released from clip 2a during the operation ofthe spectroscope, the electrode falls into funnel 47, where it quicklyassumes a flat position adjacent the lower funnel wall and then slidesthrough passage 50a and across region 55, its momentum carrying itthrough opening 58 and into receptacle 49. Funnel 49 is given a shapeand dimensions which will reduce to a minimum the possibility ofelectrodes becoming jammed therein.

Whenever it is desired to empty receptacle 49, it is only necessary tomove plug 56 into its sealing position, to allow air to enter throughorifice 48a and to detach receptacle 49 by extracting the ends ofstirrup 49a from their respective notches in the end of air lock 48.

Once receptacle 49 has been emptied it is only necessary to replace it,to relatch stirrup 49a, and to evacuate the regions in order to beprepared for another series of test runs.

The device described above thus represents a complete system forhandling spectroscope test electrodes with a greater speed, ease andcertainty than was known in the prior art. It also permits electrodes tobe interchanged without disturbing the vacuum existing in thespectroscope chamber. As an example of the capability of the assembly ofthe present invention, it has been found possible to exchange electrodesin less than 20 seconds, to carry out one complete analysis run in lessthan three minutes, and to carry out analyses on 60 sample electrodes inthree to four hours, all without unduly hurrying. It may be readilyappreciated that such a capability greatly enhances the accuracy ofresults because the shorter the time elapsed between any two tests, theless the state of the medium within the spectroscope chamber can change,and hence the greater will be the uniformity of the results.

While one form of the present invention has here been shown anddescribed, it should be obvious that many variations and modificationscould be made thereto without departing from the spirit thereof. It istherefore intended that the coverage of this invention be limited onlyby the scope of the appended claims.

What we claim is:

1 In a spectroscope comprising a test chamber, within Which a vacuum ismaintained and which has a plurality of openings in its walls, electrodehandling means comprising:

(a) electrode gripping means disposed within said chamber fortemporarily holding an electrode in the position required for theperformance of spectrum analysis;

(b) electrode manipulating means extending through one of said chamberopenings and having one end which cooperates with said electrodegripping means for releasing the electrode held therein, saidmanipulating means comprising stop means which controls the length of anelectrode which will protrude from said gripping means; i

(c) electrode inserting means, extending through a second one of saidchamber openings, for passing electrodes from the region surroundingsaid chamber to the interior of said chamber without disturbing theconditions of the vacuum therein;

(d) electrode receptacle means extending through a third one of saidchamber openings and having an opening disposed directly below saidelectrode gripping means; and

(e) a plurality of air tight seals associated with each of said chamberopenings for rendering the joints air tight between the said openingsand the above recited devices with which they are associated.

2. A device as claimed in claim 1 wherein said electrode gripping meanscomprises a pair of gripping jaws and a pair of flat springs each ofwhich is connected to a respective one of said jaws so as to urge saidjaws towards one another, and said electrode manipulating meanscomprises: a shaft having a longitudinal axis which is parallel to thatof an electrode held in said gripping means; said one end being attachedto said shaft and being in the form of a flat blade; said shaft beingslidably and rotatably mounted in said chamber opening for insertingsaid end between said flat springs and separating said aws.

3. In a spectroscope comprising a vacuum chamber for the production ofspectrograms, electrode introducing means comprising:

(a) housing means rigidly and impermeably connected to said chamber andhaving an inner end in communication with the interior of said chamber,an outer end in communication with the environment exterior to saidchamber, and an opening in said inner end through which the interior ofsaid chamber communicates with the interior of said housing;

(b) electrode transfer means movably and impermeably mounted in saidhousing and having an electrode carrying passage which extendstherethrough so that each of its ends communicates with a respective oneof said ends of said housing means, said transfer means being movable,with respect to said housing means, from a position where said passageis isolated from the interior of said chamber to a position where saidpassage is in communication therewith; and

(c) closing means cooperating with said electrode transfer means forisolating said passage from the environment surrounding said chamber.

4. A device as recited in claim 3 wherein said housing means iscylindrical and the said opening at its inner end is displaced by thesame distance from the longitudinal axis of said cylinder as is saidelectrode carrying passage.

5. A device as recited in claim 4 wherein said electrode carrying meanscomprises an extension in the direction towards the interior of saidchamber and said electrode carrying passage passes through saidextension.

6. A device as recited, in claim 5 wherein the outer cross-section ofsaid extension is inscribable within said opening.

7. A device as recited in claim 3 wherein said closing means has alongitudinal canal which is aligned with said electrode carrying passagewhen said closing means isolates said passage.

8. A device as recited in claim 7 wherein said closing means furthercomprises a push member slidably disposed with said canal for connectingsaid canal and said passage into said chamber.

9. A device as recited in claim 7 wherein said closing means furthercomprises a connector in communication with said canal for connectingsaid canal and said passage to a vacuum pump.

10. In a spectroscope comprising a vacuum chamber within which aredisposed openable electrode holder means and holder opening means,electrode recovery means comprising:

(a) funnel means disposed within said chamber directly below said holderand having a generally vertical passage for guiding the travel ofelectrodes released by said holder;

(b) air lock means passing through the wall of said chamber and having apassage therethrough for permitting electrodes to pass out of saidchamber, said air lock being connected to said funnel so that the lowerend of said funnel passage communicates with one end of said air lockpassage; and

(c) detachable receptacle means disposed outside of said chamber andconnected to said air look so as to be in communication with the otherend of said air lock passage for receiving and retaining electrodeswhich have passed through said funnel.

11. A device as recited in claim 10 wherein said air lock meanscomprises movable sealing means for isolating said funnel means from theregion in communication with said other end of said air lock passagewhen said region is at a pressure which differs from that present insaid vacuum chamber.

References Cited UNITED STATES PATENTS 4/1962 Bishop et al 2504l.99/1965 Hickam 250-413

1. IN A SPECTROSCOPE COMPRISING A TEST CHAMBER, WITHIN WHICH A VACUUM ISMAINTAINED AND WHICH HAS A PLURALITY OF OPENINGS IN ITS WALLS, ELECTRODEHANDLING MEANS COMPRISING: (A) ELECTRODE GRIPPING MEANS DISPOSED WITHINSAID CHAMBER FOR TEMPORARILY HOLDING AN ELECTRODE IN THE POSITIONREQUIRED FOR THE PERFORMANCE OF SPECTRUM ANALYSIS; (B) ELECTRODEMANIPULATING MEANS EXTENDING THROUGH ONE OF SAID CHAMBER OPENINGS ANDHAVING ONE END WHICH COOPERATES WITH SAID ELECTRODE GRIPPING MEANS FORRELEASING THE ELECTRODE HELD THEREIN, SAID MANIPULATING MEANS COMPRISINGSTOP MEANS WHICH CONTROLS THE LENGTH OF AN ELECTRODE WHICH WILL PROTRUDEFROM SAID GRIPPING MEANS; (C) ELECTRODE INSERTING MEANS, EXTENDINGTHROUGH A SECOND ONE OF SAID CHAMBER OPENINGS, FOR PASSING ELECTRODESFROM THE REGION SURROUNDING SAID CHAMBER TO THE INTERIOR OF SAID CHAMBERWITHOUT DISTURBING THE CONDITIONS OF THE VACUUM THEREIN; (D) ELECTRODERECEPTACLE MEANS EXTENDING THROUGH A THIRD ONE OF SAID CHAMBER OPENINGSAND HAVING AN OPENING DISPOSED DIRECTLY BELOW SAID ELECTRODE GRIPPINGMEANS; AND (E) A PLURALITY OF AIR TIGHT SEALS ASSOCIATED WITH EACH OFSAID CHAMBER OPENINGS FOR RENDERING THE JOINTS AIR TIGHT BETWEEN THESAID OPENINGS AND THE ABOVE RECITED DEVICES WITH WHICH THEY AREASSOCIATED.